Aluminum alloys



Fatenteol @ct. El, 1933 UNITED STAUTES PATENT QFFICE Aluminum Company ofAmerica, Pittsburgh,

Pa, a corporation of Pennsylvania No Drawing. Original applicationSeptember 21,

1932. Serial No. 634,155. Divided and this application N ovembcr 1Claim.

This invention relates to aluminum base alloys containing magnesium. Theinvention has for its object the improvement of alloys of this class Iby the addition thereto of about 0.05 to 2.0 per 5 cent by Weight ofcalcium. The invention is particularly concerned with the specificalloys hereinafter described.

The claim of this application covers certain matter divided from mycopending application Serial No. 634,155 which is, in part, acontinuation of my copending application Serial No. 595,231. Inventionsdisclosed but not claimed herein are claimed in my copendingapplications Serial Nos. 595,231, filed February 25, 1932, 645,108 to645,116 inclusive, and 645,118 to 645,- 125 inclusive, all filedNovember 30, 1932.

Considerable diiiculty has heretofore been encountered in attempts tocommercially produce castings of aluminum base alloys containingsubstantial amounts of magnesium. This dihiculty is encountered both inthe making of sand castlugs and permanent mold or chill-mold castings,although the nature of the difiiculty difiers somewhat in each case. Inthe case of sand castings there occurs a reaction between the moltenaluminum base alloy containing magnesium and the ordinary sand-moldmaterials, or vapors generated therefrom. There is also a reaction withthe atmosphere. In addition, the magnesium-containing aluminum basealloy does not flow freely through narrow mold sections at ordinarypouring temperatures and, if the pouring temperature be raised; thesolidified alloy is unsound. If the aluminum base alloy containingmagnesium be cast in a chill-mold the reaction effect is minimized tosome extent, but the troubles arising from cold-shuts and mis-runs areaccentuated because of the more rapid chilling of the molten metal. Theconsiderations apply to the aluminum base alloys specifically disclosedherein and particularly to such alloys.

j I have discovered that when. calcium is added to aluminum base alloysof the type and composition herein described, these difficulties are, toa considerable extent, eliminated. The calcium should be present inamounts ranging from 0.05 per cent to 2.0 per cent by weight subject tospecific considerations as hereinafter disclosed.-

30, 1932. Serial No.

(Cl. 75--l) to the free passage of the metal through the apertures.Regardless of the cause of this low fluidity, I have discovered that theaddition to the alloy of relatively small amounts of calcium in thepreferred range between 0.05 to 0.5 per 00 cent, improves the castingcharacteristics to a very considerable extent and simultaneously effectsa reduction of the scum or dross collecting at or near the surface. Inthe casting of articles in sand molds, I prefer to add calcium inamounts less than about 0.5 per cent except in instances Where somereduction of tensile strength or other mechanical or tensile property isimmaterial. In amounts of more than 0.5 per cent the calcium additionproduces the advantages enumerated herein but has a tendency to lowersome of the physical properties of the alloys. This effect is notharmful when calcium is present in amounts of about 0.5 per cent orless, but when high strength is not a desideratum the calcium may beused in amounts up to about 2.0 per cent. In intricate permanent moldcastings, where casting troubles are very serious if no calcium beadded, the improved physical properties obtained coincident with theproduction of good castings more than ofiset the diminution inproperties which might otherwise result from the use of the calcium.

I have also discovered that when calcium is added to aluminum basealloys containing magnesium, the amount of gas evolved; duringsolidification of the alloys is considerably reduced. When from about0.05 per cent to. 2.0 per cent by weight of calcium is added to thealloys, the amount of gas evolved becomes less marked with increasingcalcium content and the reduction of gas evolution may be so marked thatthe molten metal cools to the solidification temperature with a smoothmirror-like surface. I prefer to restrict the amount of calcium added to2.0 per cent or less since above this amount the physical properties ofthe alloys may be too seriously affected. If the best physicalproperties are desired with an improved, although not complete, degreeof gas prevention, I keep the calcium content of the alloys between 0.05per cent and about 0.5 per cent.

In the application of the principles of my invention. I have determinedthat certain aluminum base alloys containing magnesium are particularlybenefitted thereby. For example, a very useful aluminum base alloy isone containing about 2.0 to 9.0 per cent of magnesium and. 0.05 per centto 2.0 per cent of calcium, as is also aluminum base alloy containingabout 2.0

'cobalt,

to 15.0 per cent of magnesium, 0.1 to 3.5 per cent of cobalt, and 0.5 to2.0 per cent of calcium to which other elements such as copper,antimony, bismuth, nickel, manganese, and other well known alloyingelements may be added to produce particular properties therein.

Likewise is the addition of 0.05 to 2.0 per cent of calcium beneficialto those aluminum base alloys which contain about 2.0 to 15.0 per centof magnesium and 0.05 to 0.4 per cent of at least one of the class ofmetals here defined as antimony and bismuth, such alloys being veryuseful where use at high temperatures is contemplated. Calcium maylikewise be added to improve such alloys when they contain, in additionto magnesium and antimony and/or bismuth, one or more of such alloyingelements as copper, nickel, manganese, zinc, etc. which may be added tomodify or produce a specific property in the alloy.

The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of aluminum base alloys which contain as majoralloying elements about 2.0 to 10.0 per cent of magnesium and about 0.2to 5.0 per cent of nickel. For instance, an aluminum base alloycontaining 3.0 to 7.5 per cent of magnesium and 0.2 to 2.0 per cent ofnickel is improved by the addition of 0.05 to 2.0 per cent of calcium asis, likewise, this same alloy when it also contains about 0.05 to 0.4per cent of one or more of the class of elements composed of antimonyand bismuth. Another excellent aluminum base alloy prepared inaccordance with the principles of my invention is one containing 3.0 to8.0 per cent of magnesium, 0.5 to 4.0 per cent of nickel. 0.5 to 4.0 percent of manganese, and 0.05 to 2.0 per cent of calcium, which alloy mayalso be improved, particularly for application at high temperatures, bythe additionof 0.05 to 0.4 per cent of at least one of the class ofelements composed of antimony and bismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium, andaluminum base alloys containing magnesium, nickel, and copper, as wellas those alloys containing magnesium, nickel, and cobalt. Examples maybe given of aluminum base alloys containing 2.0 to 10.0 per cent ofmagnesium, 0.2 to 5.0 per cent of nickel, 0.5 to 3.5 per cent ofchromium, and 0.05 to 2.0 per cent of calcium.

An aluminum base alloy containing 3.0 to 8.0 per cent of magnesium, 0.5to 3.5 per cent of nickel, 0.5 to 3.5 per cent of chromium, and 0.05 to2.0 per cent of calcium has excellent casting properties and the hightemperature properties of this alloy can be favorably affected by theaddition of 0.05 to 0.4 per cent of at least one of a class of elementscomposed of bismuth and antimony. Examples may be given of aluminum basealloy containing 2.0 to 10.0 per cent of magnesium, 0.2 to 5.0 per centof nickel, 1.0 to 6.0 per cent of copper, and 0.05 to 2.0 per cent ofcalcium. An excellent alloy of this type is one containing 3.0 to 8.0per cent of magnesium, 0.5 to 5.0 per cent of nickel, 1.0 to 6.0 percent of copper, and 0.05 to 2.0 per cent of calcium with or without 0.05to 0.4 per cent of at least one of the class of elements composed ofantimony and bismuth and with or without the further addition of 0.5 to3.5 per cent of at least one of a class of elements composed of cobaltand chromium, and with or without the further addition of 0.1 to 1.0 percent of at least one of a class of elements composed of tungsten,vanadium, molybdenum, titanium, and zirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent of calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class of elementscomposed of antimony and bismutl is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel, 0.1 to 3.0per cent cobalt, and 0.05 to 2.0 per cent calcium.

Among other magnesium-containing aluminium base alloys which I havefound to be particularly benefited by the presence of calcium arenumbered the aluminum base alloys containing 3.0 to 8.0 per cent ofmagnesium, 1.0 to 6.0 per cent of copper, 0.5 to 3.5 per cent ofchromium, and 0.05 to 2.0 per cent of calcium, with or without theaddition of 0.05 to 0.4 per cent of at least one of a class of metalscomposed of antimony and bismuth and with or without the addition ofother alloying elements.

The alloys herein described may be produced by the usual methods ofalloying metals. The calcium is preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The aluminum used in preparing the alloys may be pure or itmay contain the impurities found in commercial grades of this metal.Ordinarily a good commercial grade of virgin aluminum will giveexcellent results and is preferable.

Having thus explained and described my invention, I claim:

A metallic alloy consisting of 3.0 to 8.0 per cent by weight ofmagnesium, 0.5 to 5.0 per cent by weight of nickel, 0.5 to 3.5 per centby weight of cobalt, 0.5 to 5.0 per cent by weight of copper, and 0.05to 2.0 per cent by weight of calcium, the balance being aluminum.

ROBERT T. WOOD.

CERTIFICATE OF CORRECTION.

Patent No. 1,932,863. I October 31, 1933.

ROBERT T. WOOD.

It ie hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,line 2, for "0.5" read 0.05; and that the said Letters Patent should .beread with this cor- V rection therein that the same may conform to therecord of the case in the Patent Office. r I Signed and sealed this 12thday of December, A. D. 1933.

F. M. Hopkins (Seal) Acting Commissioner of 131MB.

